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<title>Using as: Xtensa Directives</title>

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<a name="Xtensa-Directives"></a>
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<a name="Directives-3"></a>
<h4 class="subsection">9.52.5 Directives</h4>
<a name="index-Xtensa-directives"></a>
<a name="index-directives_002c-Xtensa"></a>

<p>The Xtensa assembler supports a region-based directive syntax:
</p>
<div class="smallexample">
<pre class="smallexample">    .begin <var>directive</var> [<var>options</var>]
    &hellip;
    .end <var>directive</var>
</pre></div>

<p>All the Xtensa-specific directives that apply to a region of code use
this syntax.
</p>
<p>The directive applies to code between the <code>.begin</code> and the
<code>.end</code>.  The state of the option after the <code>.end</code> reverts to
what it was before the <code>.begin</code>.
A nested <code>.begin</code>/<code>.end</code> region can further
change the state of the directive without having to be aware of its
outer state.  For example, consider:
</p>
<div class="smallexample">
<pre class="smallexample">    .begin no-transform
L:  add a0, a1, a2
</pre><pre class="smallexample">    .begin transform
M:  add a0, a1, a2
    .end transform
</pre><pre class="smallexample">N:  add a0, a1, a2
    .end no-transform
</pre></div>

<p>The <code>ADD</code> opcodes at <code>L</code> and <code>N</code> in the outer
<code>no-transform</code> region both result in <code>ADD</code> machine instructions,
but the assembler selects an <code>ADD.N</code> instruction for the
<code>ADD</code> at <code>M</code> in the inner <code>transform</code> region.
</p>
<p>The advantage of this style is that it works well inside macros which can
preserve the context of their callers.
</p>
<p>The following directives are available:
</p><table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="Schedule-Directive.html#Schedule-Directive" accesskey="1">Schedule Directive</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Enable instruction scheduling.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Longcalls-Directive.html#Longcalls-Directive" accesskey="2">Longcalls Directive</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Use Indirect Calls for Greater Range.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Transform-Directive.html#Transform-Directive" accesskey="3">Transform Directive</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Disable All Assembler Transformations.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Literal-Directive.html#Literal-Directive" accesskey="4">Literal Directive</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Intermix Literals with Instructions.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Literal-Position-Directive.html#Literal-Position-Directive" accesskey="5">Literal Position Directive</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Specify Inline Literal Pool Locations.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Literal-Prefix-Directive.html#Literal-Prefix-Directive" accesskey="6">Literal Prefix Directive</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Specify Literal Section Name Prefix.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Absolute-Literals-Directive.html#Absolute-Literals-Directive" accesskey="7">Absolute Literals Directive</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Control PC-Relative vs. Absolute Literals.
</td></tr>
</table>

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